Re: [Libguestfs] [PATCH nbdkit v3 5/6] server: debug: Fix error handling

Preserve errno even if the function fails. We need to set errno = err again on every exit path out of the function. Check if close_memstream failed and go to the error path if so. This is most important on Windows where close_memstream is what actually allocates the memory. But even on Unix, close_memstream (which is an alias for fclose) can return an error. Move the error-handling code to the end of the function. I added a comment above the 'fputs' explaining why exactly we're using memstream in the first place -- because it is more atomic than using multiple fprintf. See: https://listman.redhat.com/archives/libguestfs/2023-May/031456.html Thanks: Laszlo Ersek --- server/debug.c | 28 ++++++++++++++++------------ 1 file changed, 16 insertions(+), 12 deletions(-)

+ fail: + /* Try to emit what we can. */ + errno = err; + vfprintf (stderr, fs, args); + fprintf (stderr, "\n"); errno = err;